With increased competition from Amazon in the grocery sector after the Seattle-based ecommerce site acquired Whole Foods in August, Walmart is getting creative to protect its place in the grocery space, Planet Money reports.

The strategy is to “sell food Amazon can’t possibly have—that no one else has—the kind of food you might have to invent in a secret laboratory hidden in Bentonville, Ark.,” said reporter Julia DeWitt.

The results have been interesting. Walmart’s senior director of sourcing, Victor Verlage showed off a yellow-rind watermelon from the lab. The color, he said, was originally an accident, but offers a competitive edge because it’s so easy to identify.